An access control system which accepts an access from a user terminal has been known. In a mobile phone communication network, this access control system accepts a connection request from a mobile phone, which is a user terminal, and permits a connection for the mobile phone. Moreover, when the mobile phone sends a service request to a service processing system, the access control system receives an inquiry regarding the status of the connection with the mobile phone from the service processing system. Further, the access control system sends the result to the service processing system.
Due to the development of information communication systems in recent years, there are increases in the number of user terminals, the number of connections in communication systems, and the number of service processing systems. Such increases have in turn increased processing loads on access control systems.
For example, for load balancing for access control, there is a communication method in which the packets in a series of communications are always routed to pass through the same path so that a TCP connection or a user session can be maintained (see Patent Document 1, for example). In this method described in Patent Document 1, each load balancer always distributes the packets in a series of communications to the same packet gateway, and the packet gateway distributes the packets in the series of communications to multiple service providing servers capable of executing the same service. In the communication method described in Patent Document 1, as described in page 11 in the description, a session management device manages the session of a series of packet exchanges started by an access of one mobile device to a network and ended at the end of necessary communications.